Affinity chromatography plays a key role in the research, development and production of proteins including monoclonal antibodies. A filler for affinity chromatography generally contains a solid phase carrier having ligands that selectively bind to a target molecule. As the ligands on the solid phase carrier used in affinity chromatography show high selectivity to the target molecule, the affinity chromatography enables economic purification with excellent yield at a high speed, as compared to other chromatographic techniques such as ion-exchange chromatography, gel filtration chromatography, and reverse phase liquid chromatography.
Generally, in affinity chromatography for protein purification, since a strongly alkaline aqueous solution such as an aqueous solution of sodium hydroxide is used for the washing in the purification process that is repeatedly carried out, a filler for affinity chromatography is required to have high alkali resistance. Particularly, in a filler for affinity chromatography which uses a protein such as Protein A as a ligand, deterioration of the protein ligand itself, or deterioration reaction between a protein ligand and a residual reactive group on the solid phase carrier proceeds may occur during the washing or storage using a strongly alkaline aqueous solution; and therefore, an enhancement of alkali resistance and storage stability is required. Silica-based fillers that are commonly used in, for example, analytical chromatography are dissolved in a strongly alkaline aqueous solution, and therefore cannot be used repeatedly in affinity chromatography for protein purification.
Under such circumstances, it has been suggested to use agarose particles that have high hydrophilicity, high ligand activity, and a high dynamic binding capacity for a target molecule, as the solid phase carrier of a filler for affinity chromatography (Patent Documents 1 and 2).
As another solid carrier of a filler for affinity chromatography, it has been suggested to use porous particles consisting of a copolymer of styrene-divinylbenzene having excellent alkali resistance (Patent Documents 3 and 4).
Meanwhile, there have been cases in which porous particles consisting of a polymer of a hydroxyl group-containing methacrylate-based vinyl monomer are used in chromatography. However, these examples are all suitable only for gel filtration chromatography or reverse phase liquid chromatography for analytical purposes (Patent Documents 5 and 6).